A method of improving accuracy of position coordinates of a positioning device is provided. The method comprises: (A) obtaining a 3D reference solution for reference position coordinates of an positioning device by using a plurality of available radio signals emanating from an integer N number of available radio sources at time t; wherein 3D solution includes a reference 3D altitude of said positioning device at Epoch (t); (B) obtaining a barometric altitude of the positioning device at each Epoch; (C) if a trigger event occurs at Epoch (t+1), generating an updated altitude of the positioning device at Epoch (t+1) by using the reference 3D altitude obtained at Epoch (t) and by using the barometric altitude obtained at Epoch (t) and obtained at Epoch (t+1); and (D) using a position estimator to obtain 3D solution for position coordinates of the positioning device at Epoch (t+1) with improved accuracy by utilizing the updated altitude of the positioning device.